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When one looks in the box, whatever remains, however improbable, must be the cat.

Reactor

“The Enemy Within”
Written by Richard Matheson
Directed by Leo Penn
Season 1, Episode 4
Production episode 6149-05
Original air date: October 6, 1966
Stardate: 1672.1

Captain’s log: The Enterprise is in orbit around Alfa 177, performing an intense planetary survey. Geological Technician Fisher takes a fall, cutting his hand and also getting his uniform covered in yellow powder. Kirk orders him to beam up, but when he does there’s an odd transporter hiccup. Scotty and Wilson check over the transporter, and the former orders the latter to get a synchronic meter to be sure. However, the engineer feels safe beaming Kirk back to the ship, which he does. But Kirk feels a bit dizzy, so Scotty escorts the captain to his quarters—Kirk doesn’t want to leave the transporter unattended, but Scotty insists that Wilson will be right back.

After they leave, the transporter activates again, and another Kirk beams on board, but this one is underlit to make him look EEEEEEEVIL!

Wilson returns to see Evil Kirk, but the crewperson’s offer to help is ignored. Meanwhile Good Kirk goes to his quarters, where Rand has the updated ship’s manifest. He dismisses her and takes a nap.

Star Trek: The Enemy Within

Evil Kirk goes to sickbay, where McCoy cures Fisher. Evil Kirk pissily demands Saurian brandy from a nonplussed McCoy, and then lumbers drunkenly through the corridors until he reaches Rand’s quarters.

Spock comes to Kirk’s quarters to find Good Kirk with his shirt off, having woken from his nap. Spock is investigating McCoy’s report that the captain came to sickbay like a wild man, demanding brandy. Good Kirk denies it, and figures McCoy was playing a joke on Spock.

Star Trek: The Enemy Within

Later, Good Kirk (now wearing a green shirt so we can tell which is which) and Spock report to the transporter room. Sulu sent up a native animal through the transporter. But after it transported the first time, it transported again, only the second, seemingly identical animal is hostile and vicious, while the first is completely docile (and looks so very cute in Scotty’s arms). Scotty fears what would happen if a person went through the transporter, but of course the viewer already has that answer.

Rand returns to her quarters to find a lurking Evil Kirk, still guzzling brandy and leering a lot. He tries to rape her, and she responds by struggling and scratching his face. She manages to walk in front of the door when Fisher’s walking by, and the geological technician sees Evil Kirk toss her across the room. When he tries to report him, Evil Kirk jumps him and beats the crap out of him. (Fisher opens the intercom and insists on identifying himself as “Geological Technician Fisher.” If he’d just went with “Fisher,” he might have had time to get out a useful message before Evil Kirk jumped him. Stupid military protocols…)

Star Trek: The Enemy Within

Spock then reports to Good Kirk, having taken Rand’s statement and also having found the very bottle of Saurian brandy that McCoy says Kirk took in Rand’s quarters. Good Kirk goes to sickbay with Spock to talk to McCoy and Rand, leaving his cabin empty for Evil Kirk to use it to cover the scratches on his face and the blood on his knuckles.

Good Kirk doesn’t understand what’s going on—and neither does Rand, since she was sure she scratched her attacker’s face, but Good Kirk has no scratches. Fisher also insists that it was the captain. They realize that the transporter did, in fact, duplicate Kirk as well.

Star Trek: The Enemy Within

Scotty has no idea how long it’ll take to fix the transporter—which is a problem insofar as Sulu and the rest of the landing party are still on the surface, and it gets down to 120 below zero at night on Alfa 177.

Good Kirk is thumphering around, needing Spock to guide him, both in terms of how to search for Evil Kirk and reminding the captain that he can’t tell the whole truth to the crew, as they must view the captain as perfect and invulnerable. Good Kirk knows this—what he doesn’t know is why he forgot and why he needed Spock to remind him.

Star Trek: The Enemy Within

So Good Kirk simply says that there’s an impostor on board. Hearing Good Kirk make the announcement sends Evil Kirk into a rage. He attacks Wilson, stealing his phaser. Only after Wilson reports in does Spock realize that Evil Kirk knows everything Good Kirk knows. This means that Good Kirk might know where he’ll go next.

Good Kirk and Spock go to the engine room alone—Good Kirk doesn’t want anyone else in the crew to see Evil Kirk—and the three of them play cat-and-mouse for a while until the two Kirks face off. But Spock is able to stop Evil Kirk with a Vulcan nerve pinch. McCoy can’t risk giving him a tranquilizer, so he puts Evil Kirk in restraints.

Star Trek: The Enemy Within

Unfortunately, before Spock whammied him, Evil Kirk fired his phaser, damaging the transporter even further, screwing Sulu and the landing party over even more. Sulu’s doing the best he can—using phasers to heat rocks to keep them warm and keeping his sense of humor—but time’s running out.

Time’s running out for Kirk, too—Evil Kirk is dying and it’s becoming clear that Good Kirk is half the man he used to be (ahem). The strength of Evil Kirk is what makes him a good captain—although so is his intellect and compassion, which is also the source of his courage.

Scotty has gotten the transporter working again. They want to test it on the animal first. Spock and Wilson put both animals on the same platform, but while they rematerialize as a single animal, it’s as a single dead animal.

Star Trek: The Enemy Within

Spock believes the shock was too much for the creature to handle, but Kirk’s intellect should allow him to survive it. McCoy is concerned that there may be a biological or technological cause, but there isn’t time to do an autopsy on the animal or double check the transporter because of the landing party. Two of the party are unconscious, and Sulu’s in pretty bad shape, too.

Good Kirk makes the decision, and he tries to take Evil Kirk to the transporter room at phaserpoint, but Evil Kirk tricks Good Kirk, and changes shirts, and also scratches Good Kirk’s face. He goes to the bridge—after creepily offering to go to Rand’s quarters later to “explain” what happened to him—and orders Farrell to leave orbit, because there’s no hope for the landing party. Proving that Good Kirk got all the brains, it never occurs to Evil Kirk that McCoy might find Good Kirk and bring him to the bridge. It takes all of five seconds for Evil Kirk to break down and go batshit, and Good Kirk is able to convince him to come along to the transporter.

Star Trek: The Enemy Within

Spock runs him through the way they did the animal, and Kirk is one person again. His first order is to beam the landing party back. McCoy thinks they’ll live and Kirk is more than a little devastated at seeing a side of himself no one should see.

Can’t we just reverse the polarity?: The later notion of multiple transporter rooms and also of shuttlecraft and cargo bays that have transporters have not yet been conceived when this episode was written, so the only way on and off the ship is via the one transporter room, which is a problem when it breaks.

Star Trek: The Enemy Within

Fascinating: The Vulcan nerve pinch makes its debut here. The script called for Spock to “kayo” Evil Kirk, but Leonard Nimoy thought that was too undignified for Spock, so he improvised the nerve pinch.

I’m a doctor not an escalator: For the first time, McCoy says one of his signature lines, “He’s dead, Jim.” Amusingly, he says it about the space dog after the animal is reintegrated.

Star Trek: The Enemy Within

Ahead warp one, aye: Sulu is in charge of the landing party and it’s to his credit that he maintains his sense of humor as long as he can (asking for coffee or rice wine to be lowered on a rope, complaining that room service is being slow, joking about skiing season, and so on), which probably helps the morale of the three guys under his command, and also reassures the folks back on the Enterprise that he’s soldiering through.

I cannot change the laws of physics!: Scotty sees that there’s something wrong with the transporter, sends Wilson to get the scanner to check it out, but, what the heck, he beams Kirk back anyhow, and then leaves the room unattended so Evil Kirk can roam free. Good work, engineer!

Star Trek: The Enemy Within

No sex, please, we’re Starfleet: Evil Kirk immediately goes after Rand, trying to rape her and going on about the sexual tension between them. It puts Rand in an awful position, especially since he’s the captain on top of everything else, though it’s to her credit that she resists as much as she does, even wounding him.

At the very end, Spock makes a pointed and spectacularly creepy comment to Rand about how “interesting” Evil Kirk was, practically waggling his eyebrows at her. It is quite possibly Spock’s most repulsive moment in the TV series, implying that Rand probably enjoyed being raped.

Star Trek: The Enemy Within

Channel open: “Being split in two halves is no theory with me, Doctor. I have a human half, you see, as well as an alien half—submerged, constantly at war with each other. Personal experience, Doctor—I survive it because my intelligence wins over both, makes them live together.”

Spock using his dual heritage to explain the theme of the episode.

Welcome aboard: Recurring regulars DeForest Kelley, James Doohan, George Takei, and Grace Lee Whitney are back, as is Jim Goodwin as Farrell, along with Edward Madden as Fisher and Garland Thompson as Wilson. Nichelle Nichols doesn’t appear as Uhura (some unidentified man in a gold shirt is at communications), but her voice is heard over the intercom once or twice.

Star Trek: The Enemy Within

Trivial matters: This is the only Trek script by Richard Matheson, who wrote plenty of other TV scripts and movies, but who’s probably best known as a science fiction author, with such classics as I Am Legend and The Shrinking Man in his bibliography. One of his other TV scripts was for The Twilight Zone’s “Nightmare at 20,000 Feet,” one of William Shatner’s most famous pre-Star Trek roles.

Matheson’s original script didn’t have the subplot with the landing party trapped on the planet.

In addition to “He’s dead, Jim” and the nerve pinch, this episode marks the first appearance of the engine room and Kirk’s alternate green tunic (which was created to differentiate Good Kirk from Bad Kirk).

Star Trek: The Enemy Within

James Blish’s adaptation in Star Trek 8 did not include the nerve pinch as it wasn’t in the script, and that was all Blish had to work with.

Greg Cox’s novel Foul Deeds Will Rise has a character use the transporter’s ability to split someone in two like this deliberately in order to create an alibi.

This is the first of several times Kirk will be duplicated in some way: it’ll happen again in “What Are Little Girls Made Of?” “Mirror, Mirror” (kind of), “Whom Gods Destroy,” and Star Trek VI: The Undiscovered Country.

In his log entry, Spock refers to himself as “Second Officer Spock,” even though he’s obviously the second-in-command, which would make him first officer.

During the confrontation on the bridge, director Leo Penn was forced to reverse the image of Evil Kirk due to a blocking error. Unfortunately, that meant that, in closeups, Evil Kirk’s scratches were on the wrong side of his face.

Plenty of other science fiction TV shows have done the split-into-good-and-evil thing. Two of your humble rewatcher’s favorites are Red Dwarf’s “Demons and Angels,” which goes to hilarious extremes with the “high” and “low” versions of the cast, and Farscape’s “My Three Crichtons,” in which the “good” (intellectual) version is actually the asshole and the “bad” (caveman-like) version is actually the “good” one.

Star Trek: The Enemy Within

To boldly go:I’m Captain Kirrrrrrrrk!” This episode is nonsensical and stupid on the face of it. Pretty much the minute the transporter proved itself capable of something this horrible, every transporter in the Federation should’ve been taken offline until it was fixed so that this sort of thing could never happen again. (And maybe they were between episodes?) But also, how could the transporter have done this? From whence did it create the extra mass? Some minor lip service is paid to how weak both Kirks are, to the point where McCoy says Evil Kirk is dying, and Good Kirk is in pretty bad physical shape by the end of it, but that’s about it.

However, while this makes no sense from a scientific standpoint, it makes for a good story. Examining the different elements of humanity and sometimes splitting them in twain has been the subject of fiction for ages, most famously in Robert Louis Stevenson’s Strange Case of Dr. Jekyll and Mr. Hyde, which was Richard Matheson’s primary inspiration for the story.

Star Trek: The Enemy Within

Interestingly, this episode gives us the first look at the series’ staple of Spock and McCoy serving as the two sides of Kirk’s brain, with Spock on one side and McCoy the other. However, it’s not the usual Spock is rational/McCoy is emotional argument that we’ll see more often, as McCoy’s actually the one preaching caution and scientific inquiry rather than rush to try to reintegrate Kirk before he can do an autopsy on the animal, while Spock is barreling ahead in part because of the danger to the landing party.

But Spock can actually speak to two warring halves in one body, the first time his status as a halfbreed is examined in depth. In particular, I like the fact that he couches the differences between the Kirks in terms of what humans refer to as “good” and “bad,” because it’s really not that simple. Evil Kirk has lust and no filter and arrogance and is basically all id—but those are useful qualities in moderation. Evil Kirk has all of Kirk’s passion, which is a critical part of his personality, but not negative in the abstract. But Good Kirk has the intellect, the compassion, the filter—but not the ability to be decisive. It’s not so much good and evil as it is aggressive versus passive, and I wish Spock had taken it a step further and not just cast it as “Earth emotions,” but pointed out how the terms “good” and “evil” are imprecise.

Star Trek: The Enemy Within

It’s risky doing an episode where someone has to be out of character (twice over!) so early in a show’s run, but it works mainly because of William Shatner. Both versions of Kirk have recognizable qualities we’ve seen in Jim Kirk in the previous four episodes, just subdued in Good Kirk and over the top in Evil Kirk. But he does an excellent job here, as the different shirts aren’t even necessary to tell the two Kirks apart—Shatner’s body language does it just fine.

Finally, I wish to once again point out the easy camaraderie amongst the crew of the Enterprise, a hallmark of the early part of the show that was sadly lost as time went on. Besides Sulu’s bantering right up until he’s too cold to talk coherently, we also have the wonderful “What happened to you?” exchange between Wilson and Fisher in the transporter room. I really wish those little touches that showed the greater community of the Enterprise had remained the norm.

Warp factor rating: 7

Next week:The Man Trap


Keith R.A. DeCandido has a story in IDW’s forthcoming anthology The X-Files: Trust No One, edited by Jonathan Maberry. His story is a second-season tale called “Back in El Paso My Life Will be Worthless,” and the book is available for preorder from Amazon.

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Keith R.A. DeCandido

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Keith R.A. DeCandido has been writing about popular culture for this site since 2011, primarily but not exclusively writing about Star Trek and screen adaptations of superhero comics. He is also the author of more than 60 novels, more than 100 short stories, and around 50 comic books, both in a variety of licensed universes from Alien to Zorro, as well as in worlds of his own creation. Read his blog, follow him on Facebook, The Site Formerly Known As Twitter, Instagram, Threads, and Blue Sky, and follow him on YouTube and Patreon.
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